Analysis of Marketplace enrollment has focused primarily on the initial 2014 open enrollment period. But as the second open enrollment period ends—and as open enrollment periods shorten in future years—special enrollment periods (SEPs) will warrant increasing attention. This paper analyzes the legal framework, limited enrollment data, and first year special enrollment experiences in five State-Based Marketplaces (SBMs) and finds that Marketplace systems and consumer outreach and enrollment efforts did not yet match the significant potential for SEP enrollment. The paper identifies several themes that may help policymakers improve SEP enrollment systems in 2015 and beyond.